Hyperphosphatemia is a particular problem of patients with chronic renal insufficiency or chronic kidney disease (CKD). Approximately 70% of patients with end stage renal disease (ESRD) on renal dialysis therapy require treatment for hyperphosphatemia. This condition can lead to severe bone problems and metastatic calcification of skin and major organs and is associated with significant morbidity and mortality. Conventional dialysis fails to reduce the levels of phosphate in the blood, so that levels rise in time. Elevated phosphate levels are treated using a combination of dietary restrictions and phosphate-binding agents.
Another problem of patients with chronic renal insufficiency is secondary hyperparathyroidism. It is also important in patients with chronic renal insufficiency to avoid and treat secondary hyperparathyroidism.
Certain forms of lanthanum carbonate have been used to treat hyperphosphatemia in patients with renal failure (see, e.g., JP 1876384).
U.S. Pat. No. 5,968,976, owned by the assignee of the present invention, describes the preparation and use in a pharmaceutical composition of certain hydrates of lanthanum carbonate for the treatment of hyperphosphatemia.
However, lanthanum carbonate has a tendency to degrade to lanthanum hydroxycarbonate. This process is accelerated by moisture and heat. There is a need in the art to prevent this degradation because current regulatory requirements preclude detectable decarboxylation for administration to patients. The present invention is based on the surprising finding that monosaccharides or disaccharides significantly retard the degradation of lanthanum carbonate, whereas more complex saccharides (e.g., corn starch and β-cyclodextrins) do not. Stabilized compositions of lanthanum carbonate can be used in pharmaceutical preparations and for treating subjects having hyperphosphatemia.